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      Visual Hallucinations in the Psychosis Spectrum and Comparative Information From Neurodegenerative Disorders and Eye Disease

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          Abstract

          Much of the research on visual hallucinations (VHs) has been conducted in the context of eye disease and neurodegenerative conditions, but little is known about these phenomena in psychiatric and nonclinical populations. The purpose of this article is to bring together current knowledge regarding VHs in the psychosis phenotype and contrast this data with the literature drawn from neurodegenerative disorders and eye disease. The evidence challenges the traditional views that VHs are atypical or uncommon in psychosis. The weighted mean for VHs is 27% in schizophrenia, 15% in affective psychosis, and 7.3% in the general community. VHs are linked to a more severe psychopathological profile and less favorable outcome in psychosis and neurodegenerative conditions. VHs typically co-occur with auditory hallucinations, suggesting a common etiological cause. VHs in psychosis are also remarkably complex, negative in content, and are interpreted to have personal relevance. The cognitive mechanisms of VHs in psychosis have rarely been investigated, but existing studies point to source-monitoring deficits and distortions in top-down mechanisms, although evidence for visual processing deficits, which feature strongly in the organic literature, is lacking. Brain imaging studies point to the activation of visual cortex during hallucinations on a background of structural and connectivity changes within wider brain networks. The relationship between VHs in psychosis, eye disease, and neurodegeneration remains unclear, although the pattern of similarities and differences described in this review suggests that comparative studies may have potentially important clinical and theoretical implications.

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          Strauss (1969) revisited: a psychosis continuum in the general population?

          Although dichotomously defined for clinical purposes, psychosis may exist as a continuous phenotype in nature. A random sample of 7076 men and women aged 18-64years were interviewed by trained lay interviewers with the Composite International Diagnostic Interview (CIDI). Those with evidence of psychosis according to the CIDI were additionally interviewed by psychiatrists. For the 17 CIDI core psychosis items, we compared a psychiatrist's rating of hallucinations and/or delusions (Clinical Psychosis; sample prevalence 4.2%) with three other possible positive CIDI ratings of the same items: (i) symptom present, but not clinically relevant (NCR Symptom; sample prevalence 12.9%); (ii) symptom present, but the result of drugs or somatic disorder (Secondary Symptom; sample prevalence 0.6%); (iii) symptom appears present, but there is a plausible explanation (Plausible Symptom; sample prevalence 4.0%). Of the 1237 individuals with any type of positive psychosis rating (sample prevalence 17.5%), only 26 (2.1%) had a DSM-III-R diagnosis of non-affective psychosis. All the different types of psychosis ratings were strongly associated with the presence of psychiatrist-rated Clinical Psychosis (NCR Symptom: OR=3.4; 95% CI: 2.9-3.9; Secondary Symptom: OR=4.5; 95% CI: 2.7-7.7; Plausible Symptom: OR=5.8; 95% CI: 4.7-7.1). Associations with lower age, single marital status, urban dwelling, lower level of education, lower quality of life, depressive symptoms and blunting of affect did not differ qualitatively as a function of type of rating of the psychotic symptom, were similar in individuals with and without any CIDI lifetime diagnosis, and closely resembled those previously reported for schizophrenia. Presence of any rating of hallucinations was strongly associated with any rating of delusions (OR=6.7; 95% CI: 5.6-8.1), regardless of presence of any CIDI lifetime diagnosis. The observation by Strauss (1969. Hallucinations and delusions as points on continua function. Arch. Gen. Psychiatry 21, 581-586) that dichotomously diagnosed psychotic symptoms in clinical samples are, in fact, part of a continuum of experiences, may also apply to the general population. The boundaries of the psychosis phenotype may extend beyond the clinical concept of schizophrenia.
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            Why people see things that are not there: a novel Perception and Attention Deficit model for recurrent complex visual hallucinations.

            As many as two million people in the United Kingdom repeatedly see people, animals, and objects that have no objective reality. Hallucinations on the border of sleep, dementing illnesses, delirium, eye disease, and schizophrenia account for 90% of these. The remainder have rarer disorders. We review existing models of recurrent complex visual hallucinations (RCVH) in the awake person, including cortical irritation, cortical hyperexcitability and cortical release, top-down activation, misperception, dream intrusion, and interactive models. We provide evidence that these can neither fully account for the phenomenology of RCVH, nor for variations in the frequency of RCVH in different disorders. We propose a novel Perception and Attention Deficit (PAD) model for RCVH. A combination of impaired attentional binding and poor sensory activation of a correct proto-object, in conjunction with a relatively intact scene representation, bias perception to allow the intrusion of a hallucinatory proto-object into a scene perception. Incorporation of this image into a context-specific hallucinatory scene representation accounts for repetitive hallucinations. We suggest that these impairments are underpinned by disturbances in a lateral frontal cortex-ventral visual stream system. We show how the frequency of RCVH in different diseases is related to the coexistence of attentional and visual perceptual impairments; how attentional and perceptual processes can account for their phenomenology; and that diseases and other states with high rates of RCVH have cholinergic dysfunction in both frontal cortex and the ventral visual stream. Several tests of the model are indicated, together with a number of treatment options that it generates.
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              Schizophrenia: manifestations, incidence and course in different cultures. A World Health Organization ten-country study.

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                Author and article information

                Journal
                Schizophr Bull
                Schizophr Bull
                schbul
                schbul
                Schizophrenia Bulletin
                Oxford University Press (US )
                0586-7614
                1745-1701
                July 2014
                13 June 2014
                13 June 2014
                : 40
                : Suppl 4
                : S233-S245
                Affiliations
                1Clinical Research Centre, Graylands Hospital, North Metropolitan Health Service Mental Health , Perth, Western Australia, Australia;
                2Centre for Clinical Research in Neuropsychiatry, School of Psychiatry and Clinical Neurosciences, the University of Western Australia , Perth, Western Australia, Australia;
                3Northumberland, Tyne and Wear NHS Foundation Trust, Bensham Hospital, Gateshead and Newcastle University , Newcastle Upon Tyne, UK;
                4Institute of Psychiatry, King’s College London , London, UK;
                5Laboratoire de Neurosciences Fonctionnelles & Pathologies, Université Droit & Santé (UDSL), Univ Lille Nord de France and Centre Hospitalier Universitaire (CHU Lille), Hôpital Fontan , Lille, France;
                6School of Psychology, Newcastle University , Newcastle Upon Tyne, UK;
                7South of Tyne Early Intervention in Psychosis Service, Northumberland, Tyne and Wear NHS Foundation Trust , Newcastle Upon Tyne, UK;
                8Parnassia Psychiatric Institute , The Hague, The Netherlands;
                9Department of Psychiatry, University of Groningen , Groningen, The Netherlands;
                10University Hospital of Old Age Psychiatry , University of Bern, Bern, Switzerland;
                11Ophthalmic Research Group, School of Life and Health Sciences, Aston University , Birmingham, UK;
                12Department of Psychiatry, Sir Charles Gairdner Hospital, North Metropolitan Health Service Mental Health – Older Adult Program , Perth, Western Australia, Australia;
                13Department of Psychology: Cognition and Behaviour, University of Liège , Liège, Belgium
                Author notes
                *To whom correspondence should be addressed; Clinical Research Centre, Graylands Hospital, Private Mail Bag 1, Mount Claremont 6010, Perth, Western Australia, Australia; tel: (+61 8) 6346 6650, fax: 9384 5128, e-mail: Flavie.waters@ 123456health.wa.gov.au
                Article
                10.1093/schbul/sbu036
                4141306
                24936084
                4ca78f38-ab22-4655-b490-9c0129ccd27b
                © The Author 2014. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/3.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 23 November 2013
                : 12 February 2014
                : 12 February 2014
                Page count
                Pages: 13
                Categories
                Supplement Article

                Neurology
                visual hallucinations,schizophrenia,psychosis,cognition,imaging
                Neurology
                visual hallucinations, schizophrenia, psychosis, cognition, imaging

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